1. Field of the Invention
This invention relates to a tube assembly with a breakaway plug means. More particularly, it relates to a tube assembly having a breakaway plug means which is unlikely to be ruptured or contaminated before use, but readily broken away on use.
2. Discussion of Prior Art
In some branch tubes such as four-way branch tubes for use in combination with blood collection bags, all the branches are not used at the same time, but they are used one by one in successive steps. To prevent the flow path from being contaminated from a branch which is not in use, the branch not in use should be completely sealed with a plug or a suitable closure. Upon use of the branch which has been sealed with the plug, it is necessary that the plug be readily broken and removed to open the associated branch to allow for connection to another member such as a tube having a puncture needle.
Known in the art is a four-way branch tube with a click cap. The click cap is used as the plug that covers the opening of a branch of the branch tube. The branch can be opened simply by breaking or tearing off the click cap.
One example of the prior art click caps is illustrated in FIG. 5. A tubular body 1' has an open end 4'. A plug 2' having a frangible portion 15' is mounted on and secured to the open end portion. The plug 2' is covered with a protector 40 if desired. On use, the protector 40 or the plug 2' is manually grasped and twisted to break away or twist off the plug 2' at the frangible portion 15'. Then the tubular body 1' is ready for connection with another tubular member.
The plug is generally secured to the tubular body by a blocking bond by utilizing the heat available during autoclave sterilization, and not by an adhesive bond. To this end, the plug is formed of relatively flexible material liable to blocking such as polyvinyl chloride (PVC). The prior art tube assembly has the likelihood that it can be fractured when an external stress is accidentally applied during manufacturing or transportation or even contaminated at the fractured portion. This is particularly true when the plug is not covered with the protector. The plug formed of relatively flexible material has another problem when it is desired to twist off the plug. Click fracture of the plug is difficult because the plug as a whole is softly deformed.
Even when the plug 2' is covered with the protector 40 of rigid resin such as polypropylene to prevent accidental rupture by an external stress as shown in FIG. 5, the problem that the plug 2' itself is deformed to prevent click rupture remains unsolved. Since the plug 2' and the protector 40 are separately molded and then engaged, the use of the protector adds to the manufacturing process and makes the process complicated, increasing the cost.